In conventional technology called a geared motor, a rotation shaft of a motor and a gear mechanism are connected, and housings thereof are secured to each other by screws, as shown in Japanese Unexamined Patent Publication No. 2001-5425.
Alternatively, a motor part and a gear mechanism part are arranged separately and connected by rotation shafts of a motor, and the motor part and the gear mechanism part are divided and held in one housing in the technology, as shown in Japanese Unexamined Patent Publication No. 2003-314634.
Since a permanent magnet of the motor part rotates such that a north pole and a south pole alternately approaches an iron core slot to cause a magnetic flux of the permanent magnet to pass through an iron core, a counter-electromotive force is generated in a coil in addition to cogging torque, whereby reverse torque is applied.
Since rotational force is generated by alternately switching the north pole and the south pole at both ends of the coil, it is necessary to reverse the direction of electric current flowing in the coil, whereby the coil generates a self-induced counter-electromotive force. The electric current flowing in the coil is interrupted at each reversal of the electric current, a high surge voltage is generated at each on/off thereof, and a stronger electromagnetic wave is generated with faster rotation. For each reverse rectification of the DC current, a dead point in which the rotation force is not generated is formed to cause uneven rotation and accordingly limit the starting position. The surge voltage, the cogging torque, and the dead point are causes of electromagnetic noise generated from an armature of a DC motor.
In the conventional motor, since the positional relation of a rotor and a stator is limited and fixed, a rotation shaft cannot be designed in a free position and angle inside a motor mechanism, whereby the function, shape, and connection application method of an entire mechanical device requiring rotational torque of the motor are accordingly limited.
As shown in Japanese Unexamined Patent Publication No. 2003-314634, the technology called the geared motor is a mechanism which adjusts the rotational speed of the motor to perform torque transmission for the purpose of adjusting the torque of the motor by varying the rotational speed with a combination of a motor rotation shaft and the gear mechanism in order to increase the torque, and accordingly requires a volume of both of the motor part and a gear part.
As shown in Japanese Unexamined Patent Publication No. 2005-287215, conventional technology called an electric generator utilizing a planetary gear utilizes a planetary gear mechanism as an increaser and has a purpose of increasing the induced voltage by increasing the rotational speed of the electric generator, whereby reverse torque due to an armature reaction as the rotational load of the electric generator increases in direct proportion to a speed rotational ratio in the case where an induced electromotive force is generated by applying electric current.